Summary The goal of this project is to use electrical brain stimulation to enhance cognition by modulating traveling waves. Traveling waves are patterns of brain oscillations that propagate across the neocortex and hippocampus. They are a viable target for neuromodulation because they are important both behaviorally and physiologically, as they correlate with behavior and reveal the movement of neuronal activity across the brain. Based on our preliminary ?nding that direct electrical stimulation can enhance traveling waves, we will develop re?ned stimulation protocols for improving memory by enhancing the patterns of traveling waves that we observe in individual patients. We will conduct this work with direct invasive brain recording and stimulation in epilepsy patients. In our approach, we identify traveling waves in each patient individually and model them computationally using a network of weakly coupled Kuramoto oscillators. This model predicts the frequency and location where electrical brain stimulation should be applied to enhance each patient's endogenous waves. We then test the hypothesis that augmenting each patient's traveling waves enhances memory. In Aim 1, neurosurgical patients perform a memory task and we model the traveling waves that we observe. Then, during a rest period we apply direct electrical stimulation with multiple stimulation parameters and compare the resultant traveling waves with our model predictions. In Aim 2, we test whether the stimulation parameters that improve traveling waves also enhance memory. Here patients perform working and spatial memory tasks while we apply customized stimulation based on a computational model of their traveling waves. We will test our hypothesis that stimulation improves memory compared to sham trials and, moreover, whether the properties of stimulation-induced traveling waves correlate with memory performance at the single-trial level. By testing the ability of brain stimulation to modulate behavior via traveling waves, this project will provide causal evidence that traveling waves are important for behavior and develop a methodology for memory enhancement via customized brain stimulation.